ld: change --enable-new-dtags to only generate new dtags

The "new" dtags options have been around for 14+ years, so there
shouldn't be a need to generate both new & old tags anymore.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
gold: enable new dtags by default

The "new" dtags options have been around for 14+ years, and for all the
targets that gold supports, these flags have always existed.  So enable
them by default.

Having behavior be different from ld.bfd isn't new, and this behavior
is the "better" one, so there shouldn't be a problem based on that.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>